Do you know what brand pads come with the kit? I have seen issues with some brands of brake pads and shoes where they either put too thick of friction material on them, or use too thick of a shim on the backing plate. Perhaps a little experiment might be in order, swap the outboard pad from the left side to the right, just to see if it makes any change.
That brings me to your second question. Yes, you can remove the caliper without taking the line loose, just make sure you have a hanger of some sort (I make them from wire coat hangers) to hang the caliper up with.
